Closing the system: production of viral antigen-presenting dendritic cells eliciting specific CD8+ T cell activation in fluorinated ethylene propylene cell culture bags.

BACKGROUND: A major obstacle to anti-viral and -tumor cell vaccination and T cell immunotherapy is the ability to produce dendritic cells (DCs) in a suitable clinical setting. It is imperative to develop closed cell culture systems to accelerate the translation of promising DC-based cell therapy products to the clinic. The objective of this study was to investigate whether viral antigen-loaded monocyte-derived DCs (Mo-DCs) capable of eliciting specific T cell activation can be manufactured in fluorinated ethylene propylene (FEP) bags. METHODS: Mo-DCs were generated through a protocol applying cytokine cocktails combined with lipopolysaccharide or with a CMV viral peptide antigen in conventional tissue culture polystyrene (TCPS) or FEP culture vessels. Research-scale (< 10 mL) FEP bags were implemented to increase R&D throughput. DC surface marker profiles, cytokine production, and ability to activate antigen-specific cytotoxic T cells were characterized. RESULTS: Monocyte differentiation into Mo-DCs led to the loss of CD14 expression with concomitant upregulation of CD80, CD83 and CD86. Significantly increased levels of IL-10 and IL-12 were observed after maturation on day 9. Antigen-pulsed Mo-DCs activated antigen-responsive CD8+ cytotoxic T cells. No significant differences in surface marker expression or tetramer-specific T cell activating potency of Mo-DCs were observed between TCPS and FEP culture vessels. CONCLUSIONS: Our findings demonstrate that viral antigen-loaded Mo-DCs produced in downscaled FEP bags can elicit specific T cell responses. In view of the dire clinical need for closed system DC manufacturing, FEP bags represent an attractive option to accelerate the translation of promising emerging DC-based immunotherapies.

Protein film formation on cell culture surfaces investigated by quartz crystal microbalance with dissipation monitoring and atomic force microscopy.

Conventional cell culture surfaces typically consist of polystyrene, with or without surface modifications created through plasma treatment or protein/peptide coating strategies. Other polymers such as fluorinated ethylene propylene are increasingly being implemented in the design of closed cell culture vessels, for example to facilitate the production of cells for cancer immunotherapy. Cultured cells are sensitive to culture vessel material changes through different mechanisms including cell-surface interactions, which are in turn dependent on the amount, type, and conformation of proteins adsorbed on the surface. Here, we investigate the protein deposition from cell culture medium onto untreated polystyrene and fluoropolymer surfaces using quartz crystal microbalance with dissipation monitoring and atomic force microscopy. Both of these non-polar surfaces showed comparable protein deposition kinetics and resulted in similar mechanical and topographical film properties. At protein concentrations found in typical serum-free media used to culture dendritic cells, two deposition phases can be observed. The protein layers form within the first few minutes of contact with the cell culture medium and likely consist almost exclusively of albumin. It is indicated that initial protein film formation will be completed prior to cell settling and initial cell contact will be established with the secondary protein layer. The structural properties of the protein film surface will strongly depend on the albumin concentration in the medium and presumably be less affected by the chemical composition of the cell culture surface.

Bags versus flasks: a comparison of cell culture systems for the production of dendritic cell-based immunotherapies.

In recent years, cell-based therapies targeting the immune system have emerged as promising strategies for cancer treatment. This review summarizes manufacturing challenges related to production of antigen presenting cells as a patient-tailored cancer therapy. Understanding cell-material interactions is essential because in vitro cell culture manipulations to obtain mature antigen-producing cells can significantly alter their in vivo performance. Traditional antigen-producing cell culture protocols often rely on cell adhesion to surface-treated hydrophilic polystyrene flasks. More recent commercial and investigational cancer immunotherapy products were manufactured using suspension cell culture in closed hydrophobic fluoropolymer bags. The shift to closed cell culture systems can decrease risks of contamination by individual operators, as well as facilitate scale-up and automation. Selecting closed cell culture bags over traditional open culture systems entails different handling procedures and processing controls, which can affect product quality. Changes in culture vessels also entail changes in vessel materials and geometry, which may alter the cell microenvironment and resulting cell fate decisions. Strategically designed culture systems will pave the way for the generation of more sophisticated and highly potent cell-based cancer vaccines. As an increasing number of cell-based therapies enter the clinic, the selection of appropriate cell culture vessels and materials becomes a critical consideration that can impact the therapeutic efficacy of the product, and hence clinical outcomes and patient quality of life.

Dynamics of Endothelial Cell Responses to Laminar Shear Stress on Surfaces Functionalized with Fibronectin-Derived Peptides.

Surface endothelialization could improve the long-term performance of vascular grafts and stents. We previously demonstrated that aerosol-generated fibronectin-derived peptide micropatterns consisting of GRGDS spots over a WQPPRARI background increase endothelial cell yields in static cultures. We developed a novel fluorophore-tagged RGD peptide (RGD-TAMRA) to visualize cell-surface interactions in real-time. Here, we studied the dynamics of endothelial cell response to laminar flow on these peptide-functionalized surfaces. Endothelial cells were exposed to 22 dyn/cm2 wall shear stress while acquiring time-lapse images. Cell surface coverage and cell alignment were quantified by undecimated wavelet transform multivariate image analysis. Similar to gelatin-coated surfaces, surfaces with uniform RGD-TAMRA distribution led to cell retention and rapid cell alignment (∼63% of the final cell alignment was reached within 1.5 h), contrary to the micropatterned surfaces. The RGD-TAMRA peptide is a promising candidate for endothelial cell retention under flow, and the spray-based micropatterned surfaces are more promising for static cultures.